1. Field of the Invention
The present invention relates to a motion vector detecting apparatus and method and distribution medium and particularly to a motion vector detecting apparatus and method and distribution medium which can efficiently detect motion vector and controls power consumption.
2. Description of the Related Art
For example, in MPEG (Moving Picture Experts Group), he motion vector is detected and it is then used to encode (compress) moving picture data. As a method of detecting this motion vector, a full search block matching method can be considered.
The principle of the full search block matching method to be executed in the motion vector detecting apparatus will be explained below with reference to FIG. 8. For example, when the motion vector for retrieving frame 112 is detected from the reference frame 111, the reference block 121 is set first to the predetermined position of the reference frame 111 and the retrieving range 131 is then set to the predetermined position of the retrieving frame 112.
As explained above, when the reference block 121 and retrieving range 131 are set, a part of the same size as the reference block 121 is extracted as the predetermined specified retrieving block 122 from the retrieving range 131 and residual from the reference block 121 is calculated. Usually, the retrieving blocks 122 of the number proportional to the size of the retrieving range 131 is extracted from the retrieving range 131 in order to calculate residual between respective retrieving block 122 and the reference block 121. Accordingly, a plurality of residuals may be obtained. As explained above, the motion vector can be detected based on the positional relationship between the retrieving block 122 having the smallest value and the reference block 121 among the calculated residuals.
For example, when the reference block 121 includes an image of automobile A, if the part not including the image of automobile A indicated by a solid line in the retrieving frame 112 is extracted as the retrieving block 122, residual between the reference block 121 and retrieving block 122 becomes large. Moreover, for example, when the part including the image of automobile A indicated by the frame of dotted line in the retrieving frame 112 is extracted as the retrieving block 122 in the figure, an image of the reference block 121 becomes more similar to that of the retrieving block 122 and thereby residual becomes small value. data indicating the position in the retrieving, range 131 of the retrieving block 122 indicating the smallest residual among the residual from the reference block 121 is detected as the motion vector.
By the way, in the motion vector detecting apparatus for detecting the motion vector based on the full search blocking method, residual between the reference block 121 and a plurality of retrieving blocks 122 extracted from the retrieving range 131 is calculated. Thereby, a large amount of electrical power is consumed to execute such arithmetic operation, resulting in a problem that power consumption of the motion vector detecting apparatus becomes large. Therefore, the method for controlling power consumption by stopping the operation of the motion vector detecting apparatus when it is no longer required to detect the motion vector has been proposed by xe2x80x9cE. Miyagoshi, et al., xe2x80x9c100 mm2 0.95 W Single-Chip MPEG2 MP@ML Video Encoder with a 128 GOPS Motion Estimator and a Multi-Tasking RISC-Type Controllerxe2x80x9d, Digest of Technical Papers ISSCC""98, pp. 30-31, February 1998xe2x80x9d and xe2x80x9cM. Mizuno, et al., xe2x80x9cA 1.5 W Single-Chip MP@ML MPEG2 Encoder with Low Power Motion Estimation and Clockingxe2x80x9d, Digest of Technical Papers ISSCC""97, pp. 256-257, February 1997xe2x80x9d.
However, in such a motion vector detecting apparatus, the motion vector to be detected, for example, can be assumed to be zero vector (V(0,0)) or that similar to it. When in the case of stationary image for which the comparatively narrow retrieving range 131 is allowed or in the case of the moving image which is moving slowly, the retrieving range 131 of the same width as the moving image which moves quickly assuring large motion vector to be detected and requesting comparatively wide range as the retrieving range 131 is set.
Therefore, the process which is not particularly required (for example, arithmetic processing) is executed. As a result, here rises a problem that power consumption cannot be controlled sufficiently in the motion vector detecting apparatus.
The present invention has been proposed considering such situation and it is therefore an object of the present invention to effectively detect the motion vector and control the power consumption.
According to one aspect of the present invention, a motion vector detecting apparatus is characterized in comprising an executing means for extracting retrieving block from the retrieving range preset to the retrieving frame and then obtaining a residual between the extracted retrieving block and reference block of reference frame in order to execute the motion vector detecting process to detect the motion vector from the retrieving block which minimizes residual, an arithmetic means for calculating residual between the first image data corresponding to the reference frame and second image data corresponding to the retrieving frame and a control means for controlling the retrieving range of the executing means.
According to another aspect of the present invention, a motion vector detecting method is characterized in comprising the executing step for extracting the retrieving block from the retrieving range preset to the retrieving frame and obtaining a residual between the extracted retrieving block and reference block of the reference frame to execute the motion vector detecting process to detect the motion vector from the retrieving block which minimizes the residual, the calculating step for calculating a residual between the first image data corresponding to the reference frame and second image data corresponding to the retrieving frame and the control step for controlling the retrieving range in the executing step corresponding to the calculation result in the calculating step.
According to still another aspect, the distribution medium is characterized is distributing the computer readable program for executing the processes including the executing step for extracting the retrieving block from the retrieving range preset to the retrieving frame and obtaining a residual between the extracted retrieving block and reference block of the reference frame to execute the motion vector detecting process to detect the motion vector from the retrieving block which minimizes the residual, the calculating step for calculating a residual between the first image data corresponding to the reference frame and second image data corresponding to the retrieving frame and the control step for controlling the retrieving range in the executing step corresponding to the calculation result in the calculating step.
In the motion vector detecting apparatus, motion vector detecting method and distribution medium explained above, the retrieving block is extracted from the retrieving range set to the retrieving frame, a residual between the extracted retrieving block and reference block of reference frame is obtained, the motion vector detecting process for detecting motion vector from the retrieving block which minimizes the residual is executed, a residual between the first image data corresponding to the reference frame and the second image data corresponding to the retrieving frame is calculated and the retrieving range can be controlled corresponding to the calculation result.